Micro-electromechanical system (MEMS) pressure sensors are well known for providing excellent pressure measurements for a wide range of fluids across a wide range of low pressures. At least one such device is disclosed in U.S. Pat. No. 8,302,483 entitled, “Robust Design of High Pressure Sensor Device” issued on Nov. 6, 2012, the entire content of which is incorporated herein by reference.
Put simply, a MEMS pressure sensing device comprises essentially two dies made of silicon, one being a MEMS pressure sensing element; the other being an application specific integrated circuit (ASIC) that process signals from the sensing element and produces a signal representing a sensed pressure.
In the prior art, the two dies are mounted in a housing and connected to each other using small-diameter bond wires. The bond wires also extend between and connect the ASIC and one or more lead frames, which are conductors that pass through the housing and provide external-to-the-housing electrical connections.
While prior art MEMS pressure sensors work well, they are susceptible to both electrical and mechanical noise, which distorts the sensor's accuracy. Eliminating mechanical and electrical noise would be an improvement over the prior art.
Mechanical noise is mainly caused by how the MEMS pressure sensing element is packaged in a housing. Electrical noise is mainly caused by electric fields around the sensor and which are sensed or detected by the small lead wires that connect the MEMS piezoresistive element to a circuit that processes the output voltages from the Wheatstone bridge.
Mechanical noise can be eliminated by repackaging the MEMS pressure sensor such that it does not require a prior art housing gel, over molding or other packaging that can distort the deflection of the diaphragm. Electrical noise can be reduced by eliminating wires that tend to pick up extraneous electrical signals.